The present invention relates to a bit line select voltage generator used in nonvolatile memory devices and a data read method of a nonvolatile memory device using the same.
Recently, there is an increasing demand for nonvolatile memory devices, enabling an electrical program and erase without requiring a refresh function.
A nonvolatile memory device generally includes a memory cell array in which cells having data stored therein are arranged in matrix form, and a page buffer for writing data into specific cells of the memory cell array or reading data stored in a specific cell. The page buffer includes a bit line pair connected to a specific memory cell, a register for temporarily storing data, which will be written into the memory cell array or read from a specific cell in the memory cell array, a sensing node for sensing a voltage level of a specific bit line or a specific register, and a bit line select unit for controlling whether the specific bit line and the sensing node are connected.
In the memory cells of the nonvolatile memory device, stored data are varied depending on a threshold voltage value. It is thus important to stably maintain the threshold voltage. In particular, in recent years, distributions of the threshold voltage are set in various fields to which a multi-level cell programming method is applied. It becomes even more important to stably maintain the distributions in this instance.
However, the distributions of the threshold voltage vary depending on external conditions such as temperature. It is therefore necessary to provide a nonvolatile memory devices in which the distributions of the threshold voltage can be controlled stably irrespective of a temperature variation.